Semiconductor device including sense insulated-gate bipolar transistor

ABSTRACT

A semiconductor device of the present invention includes a semiconductor layer including a main IGBT cell and a sense IGBT cell connected in parallel to each other, a first resistance portion having a first resistance value formed using a gate wiring portion of the sense IGBT cell and a second resistance portion having a second resistance value higher than the first resistance value, a gate wiring electrically connected through mutually different channels to the first resistance portion and the second resistance portion, a first diode provided between the gate wiring and the first resistance portion, a second diode provided between the gate wiring and the second resistance portion in a manner oriented reversely to the first diode, an emitter electrode disposed on the semiconductor layer, electrically connected to an emitter of the main IGBT cell, and a sense emitter electrode disposed on the semiconductor layer, electrically connected to an emitter of the sense IGBT cell.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/599,560, filed Oct. 11, 2019, entitled SEMICONDUCTOR DEVICE INCLUDINGSENSE INSULATED-GATE BIPOLAR TRANSISTOR (Atty. Dkt. No. ROHM61-34759),which is a continuation of U.S. patent application Ser. No. 15/856,009,filed Dec. 27, 2017, entitled SEMICONDUCTOR DEVICE INCLUDING SENSEINSULATED-GATE BIPOLAR TRANSISTOR, and issued as U.S. Pat. No.10,468,499 on Nov. 5, 2019 (Atty. Dkt. No. ROHM61-34381). U.S. patentapplication Ser. No. 15/856,009 is a continuation of U.S. patentapplication Ser. No. 15/585,492, filed May 3, 2017, entitledSEMICONDUCTOR DEVICE INCLUDING SENSE INSULATED-GATE BIPOLAR TRANSISTOR,and issued as U.S. Pat. No. 9,876,092 on Jan. 23, 2018. U.S. patentapplication Ser. No. 15/585,492 is a continuation of Ser. No.14/710,184, filed May 12, 2015, entitled SEMICONDUCTOR DEVICE INCLUDINGSENSE INSULATED-GATE BIPOLAR TRANSISTOR, and issued as U.S. Pat. No.9,659,901 on May 23, 2017. Furthermore, this application claims thebenefit of priority of Japanese Application No. 2015-96808, filed on May11, 2015, and Japanese Application No. 2014-98921, filed on May 12,2014, the specifications of which are incorporated by reference hereinin their entirety.

TECHNICAL FIELD

The present invention relates to a semiconductor device including asense insulated-gate bipolar transistor (IGBT).

BACKGROUND

Semiconductor devices including sense IGBTs to monitor if a main IGBTcurrent (main current) is excessively large are disclosed in PatentDocument 1 (Japanese Patent Application Publication No. 7-240516),Patent Document 2 (Japanese Patent Application Publication No.2009-117786), and Patent Document 3 (Japanese Patent ApplicationPublication No. 2011-66121).

SUMMARY

Unlike MOSFETs, it is difficult for insulated-gate bipolar transistors(IGBTs) being bipolar elements to have current monitoring patternsstandardized by a mask ratio (sense current ratio).

Also, depending on the layout of a main IGBT and a sense IGBT, a Hallcurrent flows from the outer periphery of an active region for the mainIGBT into the sense IGBT in some cases. In that case, an overcurrent mayflow to the sense IGBT due to a shift in switching phase from an emitterof the main IGBT and the like. Because the sense IGBT stops the systemwhen a predetermined overcurrent flows as a role of current monitoring,the temporary overcurrent causes a malfunction. Therefore,conventionally, introduction of a filter circuit and margin design suchas setting a high overcurrent detection value have been necessary inorder to avoid a malfunction, and as a result, there has been a problemthat the sensitivity of the sense IGBT declines.

It is an object of the present invention to provide a semiconductordevice capable of suppressing an overcurrent different from anovercurrent that needs to be primarily detected from flowing to a senseIGBT at the turn-on time, and capable of gradually performing aswitching operation at the turn-off time.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding, reference is now made to thefollowing description taken in conjunction with the accompanyingDrawings in which:

FIG. 1 is a schematic perspective view of a semiconductor deviceaccording to a preferred embodiment of the present invention.

FIG. 2 is a schematic plan view of the semiconductor device in FIG. 1.

FIG. 3 is an enlarged view of a part surrounded by the broken line IIIin FIG. 2.

FIGS. 4A to 4C are schematic views showing cell patterns of a sense IGBTcell region and a main IGBT cell region

FIG. 5 is a sectional view presented when the semiconductor device iscut along a cutting line V-V in FIG. 3.

FIGS. 6A and 6B are sectional views presented when the semiconductordevice is cut along a cutting line VIA-VIA and a cutting line VIB-VIB inFIG. 3, respectively.

FIGS. 7A and 7B are sectional views presented when the semiconductordevice is cut along a cutting line VIIA-VIIA and a cutting lineVIIB-VIIB in FIG. 3, respectively.

FIGS. 8A to 8C are schematic views for explaining arrangements of anON-side diode.

FIGS. 9A to 9C are schematic views for explaining arrangements of anOFF-side diode.

FIG. 10 is an equivalent circuit diagram of the semiconductor device.

FIG. 11 is a graph showing a relationship between a gate resistance of asense IGBT cell and a peak sense current flowing in the sense IGBT cell.

FIG. 12 is a flowchart of a manufacturing process of the semiconductordevice.

FIG. 13 is a schematic plan view of a semiconductor package according toa preferred embodiment of the present invention.

FIG. 14 is a sectional view showing a mounting structure of thesemiconductor package in FIG. 13.

FIG. 15 is a schematic plan view of a semiconductor module according toa preferred embodiment of the present invention.

FIG. 16 is a view showing a part of the semiconductor module in FIG. 15.

FIG. 17 is a diagram showing an inverter circuit constituted by thesemiconductor module in FIG. 15.

DETAILED DESCRIPTION

Referring now to the drawings, wherein like reference numbers are usedherein to designate like elements throughout, the various views andembodiments of Semiconductor Device Including Sense Insulated-GateBipolar Transistor are illustrated and described, and other possibleembodiments are described. The figures are not necessarily drawn toscale, and in some instances the drawings have been exaggerated and/orsimplified in places for illustrative purposes only. One of ordinaryskill in the art will appreciate the many possible applications andvariations based on the following examples of possible embodiments.

The semiconductor device of the present invention includes asemiconductor layer including a main IGBT cell and a sense IGBT cellconnected in parallel to each other, a first resistance portion having afirst resistance value formed using a gate wiring portion of the senseIGBT cell and a second resistance portion having a second resistancevalue higher than the first resistance value, a gate wiring electricallyconnected through mutually different channels to the first resistanceportion and the second resistance portion, a first diode providedbetween the gate wiring and the first resistance portion, a second diodeprovided between the gate wiring and the second resistance portion in amanner oriented reversely to the first diode, an emitter electrodedisposed on the semiconductor layer, electrically connected to anemitter of the main IGBT cell, and a sense emitter electrode disposed onthe semiconductor layer, electrically connected to an emitter of thesense IGBT cell.

According to this arrangement, the first diode and the second diode areelectrically connected to the respective resistance portions in a manneroriented reversely to each other. It can thereby be selectivelydesignated according to the polarity (positive/negative) of a voltagethat is applied to the gate wiring portion whether through a first diodechannel or a second diode channel a sense gate voltage is applied.

If an arrangement is provided such that the first diode channel becomesconductive when turning on the main IGBT, at the turn-on time, a sensegate voltage is applied through the first resistance portion (first gateresistance) having a relatively low resistance. Thus, designing thefirst resistance value R_(g1) at the same level as a gate resistanceR_(gm) of the main IGBT allows bringing a timing at which the sense IGBTis turned on close to a timing at which the main IGBT is turned on. As aresult, a phase shift (phase difference) therebetween can be reduced, sothat flow of an unexpected overcurrent to the sense IGBT can besuppressed. Accordingly, current noise at the turn-on time can bereduced.

On the other hand, at the turn-off time of the main IGBT, the seconddiode channel becomes conductive, and a sense gate voltage is appliedthrough the second resistance portion (second gate resistance) having arelatively high resistance. It can thereby be suppressed that a Hallcurrent flows to the sense IGBT. Therefore, current noise at theturn-off time can be reduced, and the main IGBT can be gradually turnedoff (softly turned off).

As a result of the above, introduction of a filter circuit and margindesign such as setting a high overcurrent detection value for avoiding amalfunction can be made unnecessary. Because a gate driver can therebybe improved in detection sensitivity, the performance of a systemincluding the semiconductor device of the present invention can beimproved.

The gate wiring portion of the sense IGBT cell may include a gateelectrode formed with a predetermined wiring pattern to divide the senseIGBT cell into respective cell units, and the first resistance portionand the second resistance portion may be disposed on peripheral edgeportions of the gate electrode, respectively.

The gate electrode may include a striped pattern, and the firstresistance portion and the second resistance portion may be disposed onone end portion of the gate electrode in the striped pattern and theother end portion on a side opposite to the one end portion,respectively.

The first resistance portion may have a short wiring length compared tothat of the second resistance portion.

The first resistance portion may have a wide wiring width compared tothat of the second resistance portion.

According to this arrangement, by adjusting each of the first resistanceportion and the second resistance portion in wiring length and wiringwidth, a difference in resistance value can be simply providedtherebetween.

The first diode may be formed of a first deposition layer disposed onthe semiconductor layer, having a central portion of a firstconductivity type and a peripheral edge portion of a second conductivitytype enclosing the central portion, and the second diode is formed of asecond deposition layer disposed on the semiconductor layer, having acentral portion of a first conductivity type and a peripheral edgeportion of a second conductivity type enclosing the central portion.

According to this arrangement, by depositing and patterning asemiconductor material, the first diode and the second diode can besimply fabricated.

Any one or both of the peripheral edge portion of the first depositionlayer and the peripheral edge portion of the second deposition layer maybe formed so as to enclose an entire circumference of the centralportion inside thereof, respectively.

According to this arrangement, p-n junctions can be formed across theentire circumferences of the respective central portions of one or bothof the first deposition layer and the second deposition layer, so thatthe occurrence of a leak current can be suppressed.

Any one or both of the peripheral edge portion of the first depositionlayer and the peripheral edge portion of the second deposition layer maybe formed so as to selectively enclose a part of the central portioninside thereof, respectively.

According to this arrangement, any one or both of the first diode andthe second diode can be downsized as compared with when the entirecircumference of the central portion is enclosed by the peripheral edgeportion. As a result, the degree of freedom in the layout of any one orboth of the first diode and the second diode can be increased.

Any one or both of the first deposition layer and the second depositionlayer may be made of doped polysilicon.

Because being made of doped polysilicon allows for easy processing (suchas patterning) by an existing technique, any one or both of the firstand second diodes can be fabricated with efficiency.

The gate wiring may be connected to the central portion of the firstdeposition layer and the peripheral edge portion of the seconddeposition layer, and the semiconductor device may include a firstcontact wiring that connects the peripheral edge portion of the firstdeposition layer and the first resistance portion and a second contactwiring that connects the central portion of the second deposition layerand the second resistance portion.

The first resistance portion and the second resistance portion may beformed using a deposition layer that is the same as the first depositionlayer and the second deposition layer.

According to this arrangement, because the respective diodes and therespective resistance portions can be simultaneously formed, themanufacturing efficiency can be improved.

The gate wiring may include a main line portion and a first branchingportion and a second branching portion branching off the main lineportion, and the first branching portion and the second branchingportion may be connected to the first diode and the second diode,respectively.

The semiconductor device may include a collector electrode disposed on aback surface of the semiconductor layer, being common between the mainIGBT and the sense IGBT.

Hereinafter, preferred embodiments of the present invention will bedescribed in detail with reference to the accompanying drawings. In theaccompanying drawings, for the sake of clarification, dimensional ratiosamong components are sometimes changed from figure to figure forillustration.

FIG. 1 is a schematic perspective view of a semiconductor device 1according to a preferred embodiment of the present invention. FIG. 2 isa schematic plan view of the semiconductor device 1 in FIG. 1. In FIG.2, a gate wiring 7 is hatched for clarification.

The semiconductor device 1 has a basic form as a trench gate type IGBT.The semiconductor device 1 includes a semiconductor substrate 2 as anexample of a semiconductor layer of the present invention. Thesemiconductor substrate 2 has a structure in which a p⁺-type collectorregion 3, an n-type buffer region 4, and an n⁻-type drift region 5 arelaminated in order from its back surface toward its front surface.

On the semiconductor substrate 2, an electrode film 9 including a mainemitter electrode 6, a gate wiring 7, and a sense emitter electrode 8 isformed. On the back surface of the semiconductor substrate 2, acollector electrode 10 is formed substantially entirely thereacross. Thesemiconductor substrate 2 is formed in, for example, a rectangular shapein a plan view, and the semiconductor device 1 accordingly has arectangular shape in a plan view.

The electrode film 9 is formed in a rectangular region extendingsubstantially the entirety of the front surface of the semiconductorsubstrate 2.

The gate wiring 7 includes a pad portion 11 formed in a corner portionof the semiconductor device 1, an outer peripheral wiring portion 12 asan example of a main line portion of the present invention formed acrossthe entire circumference of an outer peripheral portion of a frontsurface of the semiconductor device 1, a plurality of (in the presentpreferred embodiment, four) main gate finger portions 13 extending fromthe outer peripheral wiring portion 12 toward an inner region of thefront surface of the semiconductor device 1, and a plurality of (in thepresent preferred embodiment, two) sense gate finger portions 14 thatare likewise extending from the outer peripheral wiring portion 12toward an inner region of the front surface of the semiconductor device1.

The front surface of the semiconductor device 1 has an oblong shapehaving a pair of short sides and a pair of long sides connecting theshort sides, and accordingly, the outer peripheral wiring portion 12 isformed in an oblong ring shape.

The main gate finger portions 13 are formed such that two each extendparallel to each other at an interval therebetween from the pair of longside parts of the outer peripheral wiring portion 12.

The sense gate finger portions 14 are formed one each from the long sidepart and short side part composing a corner portion of the outerperipheral wiring portion 12 such that a predetermined pad region 23 isdefined inside thereof. One and the other of the sense gate fingerportions 14 are, respectively, an ON-side finger 15 and an OFF-sidefinger 16 as an example of a first branching portion and secondbranching portion of the present invention. The ON-side finger 15 andthe OFF-side finger 16 are opposed such that an open portion 22 to opena part of the pad region 23 is formed between each other's distal endportions.

The sense emitter electrode 8 is disposed in a corner portion (padregion 23) of the semiconductor substrate 2 enclosed by the sense gatefinger portions 14 and the corner portion of the outer peripheral wiringportion 12, and the main emitter electrode 6 is disposed in a regioncovering substantially the entirety of the semiconductor substrate 2enclosed by the outer peripheral wiring portion 12 outside of saidcorner portion. The main emitter electrode 6, the gate wiring 7, and thesense emitter electrode 8 are formed in a mutually isolated state. Ineach section between the electrodes 6 to 8, a separation region 51 forisolation therebetween is formed.

A passivation film (not shown) is formed in a manner covering the mainemitter electrode 6, the gate wiring 7, and the sense emitter electrode8 and the front surface of the semiconductor substrate 2 exposed fromthe wiring and electrodes. In the passivation film, as shown byalternate long and two short dashed lines in FIG. 1 and FIG. 2, a gatepad opening 17, main emitter pad openings 18, and a sense emitter padopening 19 are formed.

The gate pad opening 17 is formed so as to expose a part of the padportion 11. The main emitter pad opening 18 is formed so as to expose apart of a front surface of the main emitter electrode 6. The senseemitter pad opening 19 is formed so as to expose a part of the senseemitter electrode 8. In the present preferred embodiment, a plurality of(for example, four) main emitter pad openings 18 are arrayed along along side of the rectangular front surface of the semiconductor device1.

The semiconductor device 1 is connected to a driver IC 21 (gate driver)to control IGBT operation by bonding wires 20 connected to the padopenings 17 to 19.

FIG. 3 is an enlarged view of a part surrounded by a broken line III inFIG. 2. FIGS. 4A to 4C are schematic views showing cell patterns of asense cell region 25 and a main cell region 26.

As described above, on the semiconductor substrate 2, the pad region 23a part of which is opened by the open portion 22 is formed, and thesense emitter electrode 8 is disposed in the pad region 23. The senseemitter electrode 8 has a projection portion 24 projecting from the padregion 23 to the open portion 22. The projection portion 24 issandwiched by the distal end portion of the ON-side finger 15 and thedistal end portion of the OFF-side finger 16. On the other hand, themain emitter electrode 6 is disposed outside of the pad region 23.

Moreover, as front surface regions of the semiconductor substrate 2, thesense cell region 25 is defined under the sense emitter electrode 8, andthe main cell region 26 is defined under the main emitter electrode 6.

As shown in FIGS. 4A and 4B, in the sense cell region 25 and the maincell region 26, a plurality of sense side trenches 27 and a plurality ofmain side trenches 28 are arrayed at equal intervals. Moreover, bothends of each of the sense side trenches 27 and the main side trenches 28are respectively electrically connected to the outer peripheral wiringportion 12, the main gate finger portion 13, or the sense gate fingerportion 14. By the sense side trenches 27 and the main side trenches 28,the sense cell region 25 and the main cell region 26 are defined intosense cells 31 (sense IGBT cells) and main cells 32 (main IGBT cells) instripe shapes, respectively.

Also, the sense side trenches 27, in the present preferred embodiment,include an ON-side contact portion 29 and an OFF-side contact portion 30led out from under the open portion 22 toward the ON-side finger 15 andthe OFF-side finger 16. That is, the gate wiring 7 is, as shown in FIG.3, via mutually different channels branched off from the outerperipheral wiring portion 12 being the ON-side finger 15 and theOFF-side finger 16, made to contact the ON-side contact portion 29 andthe OFF-side contact portion 30 via resistance wirings 39 and 40 to bedescribed later, respectively.

In addition, the sense side trenches 27 may be, as shown in FIG. 4C,formed in a grid shape in a manner defining matrix-shaped sense cells31. In this case, it suffices that the ON-side contact portion 29 andthe OFF-side contact portion 30 are disposed on peripheral edge portionsof a grid-shaped pattern, respectively. Of course, the grid-shaped gatetrench pattern can also be applied to the main side trenches 28 of themain cell region 26 (not shown).

As shown in FIG. 3, between the ON-side contact portion 29 and theON-side finger 15, an ON-side diode 33 as an example of a first diode ofthe present invention is interposed. On the other hand, between theOFF-side contact portion 30 and the OFF-side finger 16, an OFF-sidediode 34 as an example of a second diode of the present invention isinterposed.

Next, referring to FIG. 5 to FIGS. 9A, 9B, and 9C, the configuration ofthe semiconductor device 1 will be described in greater detail.

FIG. 5 is a sectional view presented when the semiconductor device 1 iscut along a cutting line V-V in FIG. 3. FIGS. 6A and 6B are sectionalviews presented when the semiconductor device 1 is cut along a cuttingline VIA-VIA and a cutting line VIB-VIB in FIG. 3, respectively. FIGS.7A and 7B are sectional views presented when the semiconductor device 1is cut along a cutting line VIIA-VIIA and a cutting line VIIB-VIIB inFIG. 3, respectively. FIGS. 8A to 8C are schematic views for explainingarrangements of the ON-side diode 33. FIGS. 9A to 9C are schematic viewsfor explaining arrangements of the OFF-side diode 34.

The semiconductor substrate 2 may be, for example, an n⁻-type siliconsubstrate having a thickness of 50 μm to 200 μm. The semiconductorsubstrate 2, as described above, has a structure in which the p⁺-typecollector region 3, the n-type buffer region 4, and the n⁻-type driftregion 5 are laminated.

As a p-type dopant of the p⁺-type collector region 3, for example, B(boron), Al (aluminum), and the like can be used (hereinafter, the sameapplies to p-type impurity regions). On the other hand, as an n-typedopant of the n-type buffer region 4 and the n⁻-type drift region 5, forexample, N (nitride), P (phosphorous), As (arsenic), and the like can beused (hereinafter, the same applies to n-type impurity regions).

Also, the p⁺-type collector region 3 has a dopant concentration of, forexample, 1×10¹⁵ cm⁻³ to 2×10¹⁹ cm⁻³. On the other hand, the n-typebuffer region 4 has a dopant concentration of, for example, 1×10¹⁵ cm⁻³to 5×10¹⁷ cm⁻³, and the n⁻-type drift region 5 has a dopantconcentration of, for example, 1×10¹³ cm⁻³ to 5×10¹⁴ cm⁻³.

In a front surface portion of the n⁻-type drift region 5, a p-type baseregion 35 is formed. The p-type base region 35 is formed substantiallyacross the entire region of the semiconductor substrate 2 in a mannerextending across the sense cell region 25 and the main cell region 26.The p-type base region 35 has a dopant concentration of, for example,1×10¹⁶ cm⁻³ to 1×10¹⁸ cm⁻³. Also, the p-type base region 35 has a depthof, for example, 1.0 μm to 3.0 μm from its front surface.

Moreover, the sense side trenches 27 and the main side trenches 28 areformed in a manner extending from the front surface of the semiconductorsubstrate 2 beyond a bottom portion of the p-type base region 35. Thep-type base regions 35 between adjacent sense side trenches 27 andadjacent main side trenches 28 are thereby respectively divided instripe shapes. The divided stripe-shaped semiconductor regions (Sicrystal regions) are defined as an active region of a sense IGBT and anactive region of a main IGBT, respectively.

As shown in FIG. 5, the interval Pi between the adjacent sense sidetrenches 27 (center to center distance of the sense side trenches 27)is, for example, 1.5 μm to 7.0 μm. Also, the width W₁ of the sense sidetrench 27 is, for example, 0.5 μm to 1.5 μm. Also, the interval P₂between the adjacent main side trenches 28 (center to center distance ofthe main side trenches 28) and the width W₂ of the main side trench 28are the same as the interval P₁ between the sense side trenches 27 andthe width W₁ of the sense side trench 27, respectively.

On an inner surface of the sense side trench 27 and the main side trench28 and the front surface of the semiconductor substrate 2, a gateinsulating film 36 is integrally formed. The gate insulating film 36 ismade of, for example, SiO₂. Also, the gate insulating film 36 has athickness of, for example, 1100 Å to 1300 Å (in the present preferredembodiment, 1200 Å).

Moreover, in the respective trenches 27 and 28, an electrode materialmade of, for example, polysilicon or the like is buried via the gateinsulating film 36. Thereby, a sense side gate electrode 37 is formed inthe sense side trenches 27, and a main side gate electrode 38 is formedin the main side trenches 28. The respective electrodes (resistanceportions) 37 and 38 are, in the present preferred embodiment, buried upto opening ends of the respective trenches 27 and 28, respectively.

In a front surface portion of the p-type base region 35 of each of thesense cells 31 and the main cells 32, an n⁺-type emitter region 46, 47is formed. The n⁺-type emitter region 46, 47 has a depth of, forexample, 0.2 μm to 0.6 μm. Also, the n⁺-type emitter region 46, 47 has adopant concentration of 1×10¹⁹ cm⁻³ to 5>10²⁰ cm⁻³.

Also, in a front surface portion of the p-type base region 35 of each ofthe sense cells 31 and the main cells 32, a p⁺-type base contact region48, 49 is formed. The p⁺-type base contact region 48, 49 is formed in amanner extending from the front surface of the semiconductor substrate 2beyond a bottom portion of the n⁺-type emitter region 46, 47. Thep⁺-type base contact region 48, 49 has a depth of, for example, 0.2 μmto 0.8 μm. Also, the p⁺-type base contact region 48, 49 has a dopantconcentration of, for example, 5×10¹⁸ cm⁻³ to 1×10²⁰ cm⁻³.

As shown in FIGS. 6A and 6B and FIGS. 7A and 7B, on the gate insulatingfilm 36 in the front surface region of the semiconductor substrate 2, awiring film 63 including the ON-side diode 33, the OFF-side diode 34,the ON-side resistance wiring 39, and the OFF-side resistance wiring 40is formed. The wiring film 63 is formed of deposition layers (a firstdeposition layer and a second deposition layer) of doped polysilicon,and is insulated by the gate insulating film 36 with respect to thesemiconductor substrate 2. Because being made of doped polysiliconallows for easy processing (such as patterning) by an existingtechnique, the ON-side diode 33, the OFF-side diode 34, the ON-sideresistance wiring 39, and the OFF-side resistance wiring 40 can befabricated with efficiency.

The ON-side diode 33 is, as shown in FIG. 7A, disposed near the ON-sidecontact portion 29 separately from a terminal end portion of said trench27, and the ON-side resistance wiring 39 is disposed between the ON-sidediode 33 and the ON-side contact portion 29. On the other hand, theOFF-side diode 34 is, as shown in FIG. 7B, disposed near the OFF-sidecontact portion 30 separately from a terminal end portion of said trench27, and the OFF-side resistance wiring 40 is disposed between theOFF-side diode 34 and the OFF-side contact portion 30.

The ON-side diode 33, as shown in FIGS. 8A and 8B, includes a p-typeportion 41 as an example of a central portion of the present inventionbeing in a circular shape and an n-type portion 42 as an example of aperipheral edge portion of the present invention being in a quadrangularring shape enclosing the entire circumference of said p-type portion 41for example, and a p-n junction is formed along an outer periphery ofthe p-type portion 41.

Similarly, the OFF-side diode 34, as shown in FIGS. 9A and 9B, includesa p-type portion 43 as an example of a central portion of the presentinvention being in a circular shape and an n-type portion 44 as anexample of a peripheral edge portion of the present invention being in aquadrangular ring shape enclosing the entire circumference of saidp-type portion 43 for example, and a p-n junction is formed along anouter periphery of the p-type portion 43.

As above, the p-n junctions are formed across the entire circumferencesof the respective central portions (p-type portions 41 and 43) of theON-side diode 33 and the OFF-side diode 34, so that the occurrence of aleak current from the ON-side diode 33 and the OFF-side diode 34 can besuppressed.

In addition, the p-type portion 41, 43 is not necessarily in a circularshape, and may be in, for example, a triangular shape, a quadrangularshape, etc. Also, the n-type portion 42, 44 is not necessarily in aquadrangular ring shape, and may be in, for example, a circular ringshape.

Further, the entire circumference of the p-type portion 41, 43 may notbe enclosed by the n-type portion 42, 44. For example, as shown in FIG.8C and FIG. 9C, an arch-shaped n-type portion 42, 44 enclosing threesides of a quadrangular-shaped p-type portion 41, 43 may be formed, anda remaining side of the p-type portion 41, 44 may be exposed. Thisarrangement allows downsizing the ON-side diode 33 and the OFF-sidediode 34 by the regions surrounded by broken lines 45, as compared withwhen the entire circumference of the p-type portion 41, 43 is enclosed.As a result, the degree of freedom in the layout of the ON-side diode 33and the OFF-side diode 34 can be increased, and the semiconductor device1 can also be miniaturized.

The ON-side resistance wiring 39, as shown in FIGS. 8A to 8C, extendslinearly between the ON-side contact portion 29 and the ON-side diode33, and has a length L_(on) (for example, 10 μm to 50 μm) and a widthW_(on) (for example, 10 μm to 100 μm). Also, as shown in FIG. 7A, theON-side resistant wiring 39 is disposed so as to overlap the sense sidegate electrode 37 within the ON-side contact portion 29, and connectedto the sense side gate electrode 37.

Similarly, the OFF-side resistance wiring 40, as shown in FIGS. 9A to9C, extends linearly between the OFF-side contact portion 30 and theOFF-side diode 34, and has a length L_(off) (for example, 10 μm to 50μm) and a width W_(off) (for example, 10 μm to 100 μm). Also, as shownin FIG. 7B, the OFF-side resistant wiring 40 is disposed so as tooverlap the sense side gate electrode 37 within the OFF-side contactportion 30, and connected to the sense side gate electrode 37.

In the present preferred embodiment, the width W_(on) of the ON-sideresistance wiring 39 and the width W_(off) of the OFF-side resistancewiring 40 are the same as each other. On the other hand, regarding thelength, the length L_(on) of the ON-side resistance wiring 39 is shorterthan the length L_(off) of the OFF-side resistance wiring 40. That is,when the ON-side resistance wiring 39 and the OFF-side resistance wiring40 are compared, a resistance value R_(g1) (first resistance value) ofthe ON-side resistance wiring 39 having a relatively short length L_(on)is smaller than a resistance value R_(g2) (second resistance value) ofthe OFF-side resistance wiring 40 having a length L_(off) longer thanthe length L_(on). In the present preferred embodiment, the resistancevalue R_(g1) of the ON-side resistance wiring 39 is, for example, 1Ω to50Ω. On the other hand, the resistance value R_(g2) of the OFF-sideresistance wiring 40 is 400Ω to 600Ω. In addition, the resistance valueR_(g1) is preferably the same as a resistance value R_(gs) of the senseside gate electrode 37 and a resistance value R_(gm) of the main sidegate electrode 38.

An interlayer insulating film 50 is formed so as to cover substantiallythe entirety of the front surface region of the semiconductor substrate2. The interlayer insulating film 50 is made of, for example, SiO₂. Inaddition, the interlayer insulating film 50 has a thickness of, forexample, 3000 Å to 8000 Å (in the present preferred embodiment, 6000 Å).In the interlayer insulating film 50, various contact holes 52 to 59 areformed.

The main emitter electrode 6, the gate wiring 7, and the sense emitterelectrode 8 are formed on the interlayer insulating film 50. As shown inFIG. 5, the main emitter electrode 6 and the sense emitter electrode 8are connected to the n⁺-type emitter regions 47 and 46 and the p⁺-typebase contact regions 49 and 48 via the contact holes 53 and 52,respectively.

As shown in FIGS. 7A and 7B, to the p-type portion 41 of the ON-sidediode 33 exposed from the contact hole 56, the distal end portion of theON-side finger 15 is connected. On the other hand, the n-type portion 42exposed from the contact hole 57 is connected to an ON-side contactwiring 60 as an example of a first contact wiring of the presentinvention connected to the ON-side resistance wiring 39 via the contacthole 54.

To the n-type portion 44 of the OFF-side diode 34 exposed from thecontact hole 59, the distal end portion of the OFF-side finger 16 isconnected. On the other hand, the p-type portion 43 exposed from thecontact hole 58 is connected to an OFF-side contact wiring 61 as anexample of a second contact wiring of the present invention connected tothe OFF-side resistance wiring 40 via the contact hole 55. In addition,the ON-side contact wiring 60 and the OFF-side contact wiring 61 are, inthe present preferred embodiment, constructed as the electrode film 9described above.

As above, the ON-side diode 33 is connected at an anode side (p-side) tothe gate wiring 7, and the OFF-side diode 34 is connected at a cathodeside (n-side) to the gate wiring 7. That is, the ON-side diode 33 isconnected in a forward direction with respect to a positive gate voltage(reverse direction with respect to a negative gate voltage), and theOFF-side diode 34 is connected in a reverse direction with respect to apositive gate voltage (forward direction with respect to a negative gatevoltage). It can thereby be selectively designated according to thepolarity (positive/negative) of a voltage that is applied to the gateelectrode 37, 38 whether through a channel that is through the ON-sidediode 33 or a channel that is through the OFF-side diode 34 a sense gatevoltage is applied.

The shapes of the distal end portion of the ON-side finger 15 (OFF-sidefinger 16) and the ON-side contact wiring 60 (OFF-side contact wiring61) will be described in greater detail.

First, as shown in FIG. 8A, the distal end portion of the ON-side finger15 is formed along the outer periphery of the p-type portion 41 in thecenter, and in the present preferred embodiment, formed in a circularshape. The contact hole 56 is also similarly formed in a circular shape.

The ON-side contact wiring 60 is formed in a ring shape to enclose thedistal end portion of its ON-side finger 15, and connected to the n-typeportion 42 via the contact hole 57 formed along the periphery of distalend portion of the ON-side finger 15. A separation region 62 is formedin a part of the ON-side contact wiring 60. The ON-side finger 15 is,via the separation region 62, accessible to the p-type portion 41located in the central portion of the ON-side diode 33.

On the other hand, the distal end portion of the OFF-side finger 16 andthe OFF-side contact wiring 61 have shapes identical to the shapes ofthe distal end portion of the ON-side finger 15 and the ON-side contactwiring 60 that have been rotated 180°. Specifically, as shown in FIG.9A, an end portion of the OFF-side contact wiring 61 is formed along theouter periphery of the p-type portion 43 in the center, and in thepresent preferred embodiment, formed in a circular shape. The contacthole 58 is also similarly formed in a circular shape.

The distal end portion of the OFF-side finger 16 is formed in a ringshape to enclose an end portion of its OFF-side contact wiring 61, andconnected to the n-type portion 44 via the contact hole 59 formed alongthe periphery of the end portion of the OFF-side contact wiring 61. Aseparation region 64 is formed in a part of the OFF-side finger 16. TheOFF-side contact wiring 61 is, via the separation region 64, accessibleto the p-type portion 43 located in the central portion of the OFF-sidediode 34.

The electrode film 9 including the main emitter electrode 6, the gatewiring 7, the sense emitter electrode 8, the ON-side contact wiring 60,and the OFF-side contact wiring 61 is made of, for example, anAl—Si—Cu-based alloy. Also, between the semiconductor substrate 2 andthe electrode film 9, a barrier film (not shown) having, for example, aTi/TiN/Ti laminated structure may be interposed.

A collector electrode 10 formed on the back surface of the semiconductorsubstrate 2 has an AlSi/Ti/Ni/Au laminated structure laminated in orderfrom the back surface. The collector electrode 10, as shown in FIG. 5,serves as a common electrode between the sense cells 31 and the maincells 32.

An equivalent circuit of the semiconductor device 1 having beendescribed above is shown in FIG. 10. In the equivalent circuit, to thesense cell 31, a sense current that is on the order of 1/2000 (absolutevalue) of a main current flowing to the main cell 32 can be made toflow.

Moreover, according to the semiconductor device 1, with respect to apositive gate voltage, the ON-side diode 33 is connected in a forwarddirection, and the OFF-side diode 34 is connected in a reversedirection. It can thereby be selectively designated according to thepolarity (positive/negative) of a voltage that is applied to the gateelectrode 37, 38 whether through a channel of the ON-side diode 33 usingthe ON-side finger 15 or a channel of the OFF-side diode 34 using theOFF-side finger 16 a sense gate voltage is applied.

Because the ON-side diode 33 channel becomes conductive when turning onthe main cell 32, at the turn-on time, a sense gate voltage is appliedthrough the ON-side resistance wiring 39 having a short wiring lengthL_(on) compared to that of the OFF-side resistance wiring 40. Theresistance value R_(g1) of the ON-side resistance wiring 39 can thus bemade substantially the same as the resistance value R_(g)m of the mainside gate electrode 38. Therefore, a timing at which the sense cell 31is turned on can be substantially synchronized with a timing at whichthe main cell 32 is turned on. As a result, a phase shift (phasedifference) therebetween can be reduced, so that flow of an unexpectedovercurrent to the sense cell 31 can be suppressed. Accordingly, currentnoise at the turn-on time can be reduced.

On the other hand, at the turn-off time of the main cell 32, theOFF-side diode 34 channel becomes conductive, and a sense gate voltageis applied through the highly resistant OFF-side resistance wiring 40having a long wiring length L_(off) compared to that of the ON-sideresistance wiring 39. It can thereby be suppressed that a Hall currentflows to the sense cell 31 beyond the main cell region 26. Therefore,current noise at the turn-off time can be reduced, and the main cell 32can be gradually turned off (softly turned off).

The effect to reduce current noise at the turn-on and turn-off timementioned above can be proved by FIG. 11. FIG. 11 is a graph showing arelationship between a gate resistance of the sense cell 31 and a peaksense current flowing in the sense cell 31.

As shown in FIG. 11, it can be understood that at the turn-on time ofthe main cell 32, the smaller the gate resistance of the sense cell 31,the smaller the peak sense current (that is, a peak value of currentnoise). On the other hand, it can be understood that at the turn-offtime of the main cell 32, the greater the gate resistance of the sensecell 31, the smaller the peak sense current.

Thus, as in the present preferred embodiment, using the ON-sideresistance wiring 39 having a low resistance value R_(g1) as a gateresistance at the turn-on time and, at the turn-off time, using theOFF-side resistance wiring 40 having a high resistance value R_(g2) as agate resistance allows reducing current noise either at the turn-on orthe turn-off time.

As a result of the above, it becomes no longer necessary, in order toavoid the sense cell 31 malfunctioning, to introduce a filter circuitinto the semiconductor device 1 and carry out margin design such assetting a high overcurrent detection value in the driver IC 21 (refer toFIG. 1). Because the driver IC 21 can thereby be improved in detectionsensitivity, the performance of a system including the semiconductordevice 1 of the present invention can be improved.

FIG. 12 is a flowchart of a manufacturing process of the semiconductordevice 1. The manufacturing process of the semiconductor device 1 willbe described with reference to FIG. 12 and FIG. 5 to FIGS. 7A, 7B, and7C.

For manufacturing the semiconductor device 1, first, by a semiconductorsubstrate 2 (n⁻-type drift region 5) being selectively etched, senseside trenches 27 and main side trenches 28 are simultaneously formed(S1).

Next, by the semiconductor substrate 2 being thermally oxidized, a gateinsulating film 36 is formed in the entire front surface regionincluding the inner surface of the trenches 27 and 28 (S2).

Next, by, for example, an LPCVD (Low Pressure Chemical Vapor Deposition)method, polysilicon is deposited on the semiconductor substrate 2 (S3).The deposition of polysilicon is continued until the trenches 27 and 28are completely filled back and the semiconductor substrate 2 is coveredwith polysilicon.

Next, by said polysilicon being etched back, an unnecessary part of thepolysilicon is removed. A sense side gate electrode 37 and a main sidegate electrode 38 buried in the respective trenches 27 and 28 aresimultaneously formed (S4). Thereafter, by performing thermal oxidationaccording to necessity, a thermally oxidized film may be formed on anupper surface of the gate electrode 37, 38 (buried polysilicon).

Next, by, for example, an LPCVD (Low Pressure Chemical Vapor Deposition)method, polysilicon is deposited on the semiconductor substrate 2 (S5).Thereafter, into said polysilicon, a p-type dopant and an n-type dopantare respectively selectively ion-implanted.

Next, by the ion-implanted polysilicon being selectively etched, anON-side diode 33, an OFF-side diode 34, an ON-side resistance wiring 39,and an OFF-side resistance wiring 40 are simultaneously formed (S6).

Next, a p-type dopant is ion-implanted to the front surface of then⁻-type semiconductor substrate 2, and thereafter, the semiconductorsubstrate 2 is annealed. The p-type dopant is thereby subjected todrive-in diffusion, and thus a p-type base region 35 is formed (S7).

Next, an n-type dopant is ion-implanted to the front surface of thesemiconductor substrate 2, and thereafter, the semiconductor substrate 2is annealed. The n-type dopant is thereby subjected to drive-indiffusion, and thus n⁺-type emitter regions 46 and 47 are formed (S8).

Next, a p-type dopant is ion-implanted to the front surface of thesemiconductor substrate 2, and thereafter, the semiconductor substrate 2is annealed. The p-type dopant is thereby subjected to drive-indiffusion, and thus p⁺-type base regions 48 and 49 are formed (S9).

Next, an interlayer insulating film 50 is formed on the semiconductorsubstrate 2 by, for example, a CVD method (S10).

Next, on the semiconductor substrate 2, a material for an electrode film9 is deposited by, for example, a sputtering method. Then, by patterningsaid electrode film material, an main emitter electrode 6, a gate wiring7, a sense emitter electrode 8, an ON-side contact wiring 60, and anOFF-side contact wiring 61 are simultaneously formed (S11).

Next, after the semiconductor substrate 2 is reduced in thickness bygrinding from the back surface according to necessity, n-type and p-typedopants are selectively ion-implanted to the back surface of thesemiconductor substrate 2, and thereafter, the semiconductor substrate 2is annealed (in the present preferred embodiment, annealed by laser).The n-type and p-type dopants are thereby subjected to drive-indiffusion, and thus an n-type buffer region 4 and a p⁺-type collectorregion 3 are formed (S12).

Thereafter, by depositing an electrode material on the back surface ofthe semiconductor substrate 2 by, for example, a sputtering method, acollector electrode 10 is formed.

The semiconductor device 1 shown in FIG. 1 to FIGS. 7A, 7B, and 7C isobtained through the steps as above. In addition, the manufacturingprocess mentioned above merely represents a part of the manufacturingprocess of the semiconductor device 1, and the manufacturing process ofthe semiconductor device 1 may include steps that are not described inthe above.

Next, description will be given of usage modes of the semiconductordevice 1.

<Semiconductor Package>

FIG. 13 is a schematic plan view of a semiconductor package 71 intowhich the semiconductor device 1 is incorporated. FIG. 14 is a sectionalview showing a mounting structure of the semiconductor package 71 inFIG. 13.

The semiconductor package 71 includes a semiconductor device 1 andelectrodes 72 to 74, wires 75 to 77 and a resin package 78. In FIG. 13,the resin package 78 is shown by alternate long and two short dashedlines. The semiconductor package 71 is mounted on a mounting substrate79. As shown in FIG. 14, the semiconductor package 71 is used as anelectronic component that performs a switching function, a rectifyingfunction, an amplifying function, or the like, in an electrical circuitdepending on the type of the semiconductor device 1.

The electrode 72 includes a die bonding pad 80 and a lead 81. The diebonding pad 80 and the lead 81 are made of, for example, a conductivematerial such as copper.

The die bonding pad 80 is for loading the semiconductor device 1. Thedie bonding pad 80 is in a flat plate shape. The die bonding pad 80 hasan arrangement surface 801 and a back surface 802. The arrangementsurface 801 faces in a direction z1. The back surface 802 faces in adirection z2. On the arrangement surface 801, the semiconductor device 1is disposed.

Heat generated in the semiconductor device 1 is transferred to the diebonding pad 80. In the die bonding pad 80, a hole 82 that penetratesfrom the arrangement surface 801 to the back surface 802 is formed. Asshown in FIG. 13, the hole 82 may have a shape, in an x-y plane view,recessed in a direction x1 from an end portion at a side in a directionx2 of the die bonding pad 80.

The lead 81 has a shape linearly extending from the die bonding pad 80.The lead 81 is for insertion mounting. As shown in FIG. 14, the lead 81is inserted into a hole 83. The semiconductor package 71 is therebymounted on the mounting substrate 79. The hole 83 is filled with solder84 in order to fix the lead 81 to the mounting substrate 79. As shown inFIG. 13, the lead 81 has a coupling portion 811 and a terminal portion812. The coupling portion 811 and the terminal portion 812 may beintegrally molded.

The coupling portion 811 connects to the die bonding pad 80. Thecoupling portion 811 has a shape extending from the die bonding pad 80in a direction to cross the arrangement surface 801. The terminalportion 812 connects to the coupling portion 811. The terminal portion812 extends from the coupling portion 811 in the direction x1. Theterminal portion 812 has a part projecting from the resin package 78.

The electrode 73 includes a wire bonding pad 85 and a lead 86. Theelectrode 73 is positioned, in an x-y plane view, on a side in thedirection x1 of the die bonding pad 80 and on a side in a direction y1of the lead 81.

The wire bonding pad 85 and the lead 86 may be integrally molded. Thewire bonding pad 85 and the lead 86 are made of, for example, aconductive material such as cooper. The wire bonding pad 85 has asubstantially rectangular flat plate shape smaller than the die bondingpad 80. The lead 86 connects to the wire bonding pad 85. The lead 86 hasa shape linearly extending from the wire bonding pad 85 in the directionx1. The lead 86 is in juxtaposition to the lead 81. The lead 86 has apart projecting from the resin package 78. The lead 86 is for insertionmounting. As shown in FIG. 14, the lead 86 is inserted into the hole 83.The semiconductor package 71 is thereby mounted on the mountingsubstrate 79. The hole 83 is filled with solder 84 in order to fix thelead 86 to the mounting substrate 79.

The electrode 74 includes a wire bonding pad 87 and a lead 88. Theelectrode 74 is positioned, in an x-y plane view, on a side in thedirection x1 of the die bonding pad 80 and on a side in a direction y2of the lead 81.

The wire bonding pad 87 and the lead 88 may be integrally molded. Thewire bonding pad 87 and the lead 88 are made of, for example, aconductive material such as cooper. The wire bonding pad 87 has asubstantially rectangular flat plate shape smaller than the die bondingpad 80. The lead 88 connects to the wire bonding pad 87. The lead 88 hasa shape linearly extending from the die bonding pad 87 in the directionx1. The hole 83 is filled with solder 84 in order to fix the lead 88 tothe mounting substrate 79. The lead 88 is in juxtaposition to the lead81. Between the lead 88 and the lead 86, the lead 81 is positioned. Thelead 88 has a part projecting from the resin package 78. The lead 88 isfor insertion mounting. As shown in FIG. 14, the lead 88 is insertedinto the hole 83. The semiconductor package 71 is thereby mounted on themounting substrate 79.

Referring mainly to FIG. 14, the resin package 78 covers thesemiconductor device 1 and the electrodes 72 to 74. The resin package 78is made of, for example, a black epoxy resin. As shown in FIG. 14, theresin package 78 has a first surface 781 and a second surface 782.

The first surface 781 has a flat surface 783 and a tapered surface 784.As shown in FIG. 14, the flat surface 783 is a mounting surface formounting the semiconductor package 71 on the mounting substrate 79. Fromthe flat surface 783, the back surface 802 of the die bonding pad 80 isexposed. The flat surface 783 may be flush with the back surface 802,and may not be flush with the back surface 802. The tapered surface 784continues to the flat surface 783. The tapered surface 784 has a shapeheading to the outside in an x-y plane gradually in the direction z1.

The second surface 782 has a plurality of flat surfaces 785 and aplurality of tapered surfaces 786. The respective tapered surfaces 786connect to any of the plurality of flat surfaces 785. The respectivetapered surfaces 786 have shapes heading to the outside in an x-y planegradually in the direction z2. The respective tapered surfaces 786connect to the tapered surface 784.

In the resin package 78, a pin trace 787 that is recessed from one ofthe plurality of flat surfaces 785 is formed. Also, in the resin package78, a screw hole 788 is formed. Through the screw hole 788, a screw 90to fix the semiconductor package 71 to a heat dissipation plate 89 isinserted.

The wires 75 to 77 are made of, for example, a metal such as aluminum.The wire 75 is bonded to the gate wiring 7 of the semiconductor device 1and the wire bonding pad 85. The gate wiring 7 and the wire bonding pad85 are thereby conductive. The wire 76 is bonded to the main emitterelectrode 6 of the semiconductor device 1 and the wire bonding pad 87.The main emitter electrode 6 and the wire bonding pad 87 are therebyconductive. The wire 77 is bonded to the sense emitter electrode 8 ofthe semiconductor device 1 and the wire bonding pad 87. The senseemitter electrode 8 and the wire bonding pad 87 are thereby conductive.

<Semiconductor Module>

FIG. 15 is a schematic plan view of a semiconductor module 91 into whichthe semiconductor device 1 is incorporated. FIG. 16 is a view in which aresin-made base portion 92 of the semiconductor module 91 in FIG. 15 isomitted. FIG. 17 is a diagram showing an inverter circuit 101constituted by the semiconductor module 91 in FIG. 15.

The semiconductor module 91 includes mainly a base portion 92 made ofresin, electrode plates 93 and 94 (94 u, 94 v, and 94 w), and 95 made ofmetal.

The base portion 92 is formed in a case shape showing an oblong shape ina plan view, and is opened upward. The electrode plates 93 to 95 may bemade of, for example, Cu (copper), Al (aluminum), or an alloy of Cu andAl.

The semiconductor module 91 is constructed by molding the electrodeplates 93 to 95 on the base portion 92. The semiconductor module 91 maybe fixed (for example, screwed) to a heat sink via a heat dissipationsheet.

The resin electrode plates 94 u, 94 v, and 94 w are arranged side byside with their respective low step portions 96 provided with a gaptherebetween, and the electrode plate 93 is disposed opposite to endedges of the respective low step portions 96 of the side-by-sideelectrode plates 94.

The electrode plate 95 may have a communicating portion 97 extending inthe direction in which the electrode plates 94 u, 94 v, and 94 w arearranged and extending portions 98 (98 a, 98 b, 98 c, and 98 d) providedat predetermined intervals from the communicating portion 97. Thecommunicating portion 97 overlaps, along an end edge of the electrodeplate 93 opposed to the respective low step portions 96 of the electrodeplates 94, the electrode plate 93 at a predetermined clearancethereover. Moreover, the extending portions 98 overlap respective sidesof the metal electrode plates 94 u, 94 v, and 94 w. Accordingly, theextending portion 98 b extends along a gap between the electrode plates94 u and 94 v with a width across both plates, and the extending portion98 c extends along a gap between the electrode plates 94 v and 94 w witha width across both plates.

The electrode plates 94 respectively include narrow-width high stepportions 99 extending from widthwise central portions of end edgesopposed to the electrode plate 93 of their low step portions 96. Thehigh step portion 99 with an upward offset climbs over the communicatingportion 97 of the electrode plate 95 and then extends over the electrodeplate 93 with a predetermined clearance at the same height (the samelayer) as that of the electrode plate 95, and a distal end of the highstep portion 99 projects as an external connection portion 100 laterallyfrom the base portion 92 to be exposed.

The electrode plate 93 similarly includes a communicating portion 65 ina region overlapped by the communicating portion 97 of the electrodeplate 95, and has a slit 67 in a main portion 66 overlapped by the highstep portion 99 of the electrode plate 94. The slit 67 has a narrowwidth, and the high step portion 99 of the electrode plate 94 extendswith a width over the slit 67.

The communicating portion 65 of the electrode plate 93 and thecommunicating portion 97 of the electrode plate 95 are bentperpendicularly upward with a clearance therebetween maintainedrespectively at one-end sides (here, the side of the extending portion98 d) to extend upward from the base portion 92, and are then bent asexternal connection portions 68 and 69 in mutually opposite directionsand parallel to the communicating portions 65 and 97.

In terms of a phase (for example, a u-phase) of the inverter circuit101, on the main portion 66 of the electrode plate 93 located on abottom surface of the base portion 92, one set each of semiconductordevices (IGBTs) 1 p and FWDs 70 p, a total of two sets, are bonded,across the high step portion 99 of the electrode plate 94 (94 u), bysolder that is a conductive bonding material on both sides along thehigh step portion 99.

Similarly, also on the low step portion 96 of the electrode plate 94 inthe bottom surface of the base portion 92, in a region enclosed in aU-shape by the communicating portion 97 and the extending portions 98(98 a and 98 b) of the electrode plate 95, one set each of semiconductordevices (IGBTs) 1 n and FWDs 70 n are bonded by solder along therespective extending portions.

Further, at an opening side in the region enclosed in an U-shape nearthe electrode plate 94 u, gate terminals 102 n and sense emitterterminals 103 n are molded on the base portion 92 in a mannercorresponding to the sets of the semiconductor devices 1 n and the FWD70 n. On a side opposite to the communicating portion 65 near theelectrode plate 93, gate terminals 102 p and sense emitter terminals 103p are molded on the base portion 92 in a manner corresponding to thesets of the semiconductor devices 1 p and the FWD 70 p.

The semiconductor device 1 uses its solder bonded surface as acollector, and the main emitter electrode 6 on an upper surface of thesemiconductor device 1 p located on the electrode plate 93 is connectedto the high step portion 99 of the electrode plate 94 u by a pluralityof metal wires W1. Also, the gate wiring 7 on the upper surface of thesemiconductor device 1 p is connected with the gate terminal 102 p by ametal wire W3. Also, the sense emitter electrode 8 on the upper surfaceof the semiconductor device 1 is connected with the sense emitterterminal 103 p by a metal wire W4.

The FWD 70 uses its solder bonded surface as a cathode, and an anodeelectrode on an upper surface thereof is connected to the high stepportion 99 by a plurality of metal wires W2.

The main emitter electrode 6 on an upper surface of the semiconductordevice 1 n located on the metal electrode plate 94 u is connected to theextending portion 98 (98 a, 98 b) of the electrode plate 95 by aplurality of metal wires W1, and the gate wiring 7 is connected with agate terminal 102 n by a metal wire W3, and the sense emitter electrode8 is connected with a sense emitter terminal 103 n by a metal wire W4.Also, the anode electrode at an upper surface of the FWD 70 n isconnected to the extending portion 98 by a plurality of metal wiresW_(2.)

The same applies to other phases, and the inverter circuit 101 shown inFIG. 17 is thereby formed. In addition, FIG. 17 is an illustration inwhich a circuit configuration of a sense emitter is omitted.

The external connection portion 68 of the electrode plate 93 serves as aP terminal of circuit input, and the external connection portion 69 ofthe electrode plate 95 serves as an N terminal, and the respectiveexternal connection portions 100 of the electrode plates 94 (94 u, 94 v,and 94 w) serve as output terminals U, V, and W. The input/outputterminals are further connected to a bus bar or high-current cable (notshown) in an inverter device. Also, the gate terminals 102 p and 102 nand the sense emitter terminals 103 p and 103 n are connected to, forexample, a drive signal output terminal (not shown) of a drive signalcontrol board that is attached onto the base portion 92 of thesemiconductor module 91.

In corner portions of the base portion 92, middle portions between thehigh step portions 99, and near distal ends of the extending portions98, screw holes 104 are provided to make screws 105 for fixing thesemiconductor module 91 to a heat sink (not shown) insertabletherethrough. In the electrode plate 93 and the low step portions 96 ofthe electrode plates 94, cut-aways 106 and 107 are formed so as to havea predetermined clearance with the screw hole 104, and an inner wall ofthe screw holes 104 is provided as a molding resin so as to be insulatedfrom the screw 105.

Also, in a central portion of the semiconductor module 91, screwthrough-holes 108 are provided in the high step portions 99 of theelectrode plates 94 and the overlapping part of the communicatingportions 97 and 65 of the electrode plates 95 and 93 to make screws 105insertable therethrough, which is the same as with a peripheral portion.Also around the screw through-holes 108, in the high step portions 99and the communicating portions 65 and 97, holes that are larger indiameter than the screw through-holes 108 are formed, and an inner wallof the screw through-holes 108 is provided as a molding resin so as tobe insulated from the screw 105.

Although preferred embodiments of the present invention have beendescribed above, the present invention can be embodied in other forms.

For example, an arrangement may be adopted in which the conductivitytype of each semiconductor part of the semiconductor device 1 isinverted. That is, in the semiconductor device 1, the p-type parts maybe n-type and the n-type parts may be p-type.

Also, in the foregoing preferred embodiment, the difference between theresistance value R_(g1) of the ON-side resistance wiring 39 and theresistance value R_(g2) of the OFF-side resistance wiring 40 is providedby the lengths L_(on) and L_(off) of the resistance wirings 39 and 40,however, a relationship of R_(g1)<R_(g2) may be provided by making thewidth W_(on) of the ON-side resistance wiring 39 wider than the widthW_(off) of the OFF-side resistance wiring 40.

Also, in the foregoing preferred embodiment, only the arrangement of theIGBT included in the semiconductor device 1 is illustrated, however, asemiconductor device of the present invention may include elements otherthan the IGBTs (for example, MOSFETs, diodes, and the like) in a regiondifferent from a region where the IGBTs are formed.

Also, in the foregoing preferred embodiment, only the form of an IGBThaving a trench gate structure is mentioned, however, the presentinvention can also be applied to an IGBT having a planar gate structure.In this case, it suffices to provide an ON-side resistance electrode(wiring) having a relatively wide width and an OFF-side resistanceelectrode (wiring) having a relatively narrow width compared to that ofthe ON-side resistance electrode by becoming creative with the patternof a gate electrode to be formed on the semiconductor substrate 2.

The semiconductor device of the present invention can be incorporatedin, for example, a power module for use in an inverter circuit thatconstitutes a drive circuit for driving an electric motor available as apower source for an electric vehicle (including a hybrid vehicle), anelectric train, an industrial robot, and the like (for example, thesemiconductor module 91 and the like in FIG. 15 and FIG. 16).Additionally, the semiconductor device of the present invention can alsobe incorporated in a power module for use in an inverter circuit thatconverts electric power generated by a solar cell, a wind powergenerator, and other power generators (particularly, private electricgenerators) so as to be matched with electric power from commercialpower sources.

Various other design modifications can be made within the scope of thematters described in the claims.

What is claimed is:
 1. A semiconductor device comprising: asemiconductor layer including a main IGBT cell and a sense IGBT cellconnected in parallel to each other; a first channel formed by using agate wiring portion of the sense IGBT cell; and a first resistanceportion having a first resistance value incorporated in the firstchannel.
 2. The semiconductor device according to claim 1, wherein thegate wiring portion of the sense IGBT cell includes a gate electrodeformed in a predetermined wiring pattern which partitions the sense IGBTcell into each cell unit, and the first resistance portion is arrangedat a peripheral portion of the gate electrode.
 3. The semiconductordevice according to claim 2, wherein the main IGBT cell includes astriped pattern.
 4. The semiconductor device according to claim 3,wherein the sense IGBT cell monitors the amount of current flow into themain IGBT cell.
 5. The semiconductor device according to claim 4,wherein the sense IGBT cell is arranged in proximity to one side of thesemiconductor device.
 6. The semiconductor device according to claim 5,wherein the sense IGBT cell includes a striped pattern.
 7. Thesemiconductor device according to claim 6, further comprising a firstdiode electrically connected to the main IGBT cell, wherein the firstdiode is arranged at a corner portion of the semiconductor layer.
 8. Thesemiconductor device according to claim 1, further comprising a secondchannel formed by using the gate wiring portion of the sense IGBT cell,the second channel being a different channel from the first channel, andthe second channel joining with the first channel at a gate wiringportion of the main IGBT cell; a first diode incorporated in the firstchannel such that the first diode is arranged at the opposite side tothe sense IGBT cell with respect to the first resistance portion; asecond resistance portion having a second resistance value higher thanthe first resistance value incorporated in the second channel; and asecond diode incorporated in the second channel such that the seconddiode is arranged at the opposite side to the sense IGBT cell withrespect to the second resistance portion, the second diode provided in amanner oriented reversely to the first diode.
 9. The semiconductordevice according to claim 8, wherein the gate wiring portion of thesense IGBT cell includes a gate electrode formed in a predeterminedwiring pattern which partitions the sense IGBT cell into each cell unit,and the first resistance portion and the second resistance portion arearranged at a peripheral portion of the gate electrode.
 10. Thesemiconductor device according to claim 9, wherein the gate electrodeincludes a striped pattern, and the first resistance and the secondresistance are arranged on one end portion of the gate electrode in thestriped pattern and the other end portion on the opposite to the one endportion, respectively.
 11. The semiconductor device according to claim10, wherein the first resistance has a wiring length shorter than awiring length of the second resistance.
 12. The semiconductor deviceaccording to claim 11, wherein the first resistance has a wiring widthwider than a wiring width of the second resistance.
 13. Thesemiconductor device according to claim 12, wherein the first diode isformed of a first deposition layer arranged on the semiconductor layer,having a first central portion of a first conductivity type and a firstperipheral edge portion of a second conductivity type enclosing thefirst central portion, and the second diode is formed of a seconddeposition layer arranged on the semiconductor layer, having a secondcentral portion of the first conductivity type and a second peripheraledge portion of the second conductivity type enclosing the secondcentral portion.
 14. The semiconductor device according to claim 13,wherein at least one of the first peripheral edge portion of the firstdeposition layer and the second peripheral edge portion of the seconddeposition layer are formed so as to enclose an entire circumference ofthe central portion inside thereof, respectively.
 15. The semiconductordevice according to claim 13, wherein at least one of the firstperipheral edge portion of the first deposition layer and the secondperipheral edge portion of the second deposition layer are formed so asto selectively enclose a part of the central portion inside thereof,respectively.
 16. The semiconductor device according to claim 14,wherein at least one of of the first deposition layer and the seconddeposition layer is made of doped polysilicon.
 17. The semiconductordevice according to claim 16, further comprising: a gate wiringconnected to the first central portion of the first deposition layer andthe second peripheral edge portion of the second deposition layer,wherein the semiconductor device includes a first contact wiring thatconnects the first peripheral edge portion of the first deposition layerand the first resistance, and a second contact wiring that connects thesecond central portion of the second deposition layer and the secondresistance.
 18. The semiconductor device according to claim 17, whereinthe first resistance and the second resistance are formed using adeposition layer that is the same as the first deposition layer and thesecond deposition layer.
 19. The semiconductor device according to claim16, further comprising a gate wiring electrically connected to the firstresistance portion and the second resistance portion, wherein the gatewiring has a main line portion, and a first branching portion and asecond branching portion branching off the main line portion, and thefirst branching portion and the second branching portion are connectedto the first diode and the second diode, respectively.
 20. Thesemiconductor device according to claim 19, further comprising: a firstelectrode formed on the semiconductor layer, the first electrodeelectrically connected to the main IGBT cell; a first sense electrodeformed on the semiconductor layer, the first sense electrodeelectrically connected to the sense IGBT cell; and a second electrodeformed on a back surface of the semiconductor layer, the secondelectrode being common between the main IGBT cell and the sense IGBTcell.